The proposed work consists of the determination of the amino acid sequence of one of the polypeptide chains of the hemoglobin of the earthworm, Lumbricus terrestris. This large extra-cellular hemoglobin has a molecular weight of over 3 x 10 to the 6th power, and is comprised of at least 4, more probably 6, unique polypeptide chains. We also will be determining the structural differences between the chains. The molecular weights of each of the individual chains is about 15000. These studies are ultimately directed towards a better understanding of self-assembly in multi-subunit protein aggregates. The amino acid residues at the interfaces, responsible for the aggregation, should be determinable when the x-ray work is completed (now underway at Johns Hopkins University in the laboratory of Dr. Warner Love). We also plan to investigate the time-dependence of the appearance of the different, unique tadpole hemoglobin chains during the growth of the tadpole. This will entail determination of which chains are present at which stage of development and how these are partitioned in different cell populations.